#include <fstream>
#define len 800

using namespace std;

ifstream in("nrtri.in");
ofstream out("nrtri.out");
int N, rez, v[len];

int main()
{
    in >> N;
    for(int i = 0; i < N; ++i)
    {
        in >> v[i];
        for(int j = 0; j < i; ++j)
            for(int k = 0; k < j; ++k)
                if(v[i] <= v[j] + v[k] && v[j] <= v[i] + v[k] && v[k] <= v[i] + v[j])
                    ++rez;
    }
    out << rez;
    return 0;
}